From common Domestic Caps to the deadly Destroying Angel, from Octopus Stinkhorns to Scaly Hedgehogs--Arnold (Baba Yaga), a lifelong mycophile, here shares her passion for wild mushrooms. In collaboration with Swope (The Araboolies of Liberty Street), she serves up a glorious, earthy stew of fact, humor, folklore and personal stories likely to intrigue readers of all ages. Arnold weaves the serious study of mushrooms into the fabric of a gamesome, enterprising hobby, incorporating the charm of folk names alongside scientific terms and pairing activities with straightforward text. The illustrations are just as eclectic and exuberant: Arnold combines small paintings and cartoons against bright backgrounds; rustic artwork resembling woodcuts; and prints of mushroom caps. The headings include ""Mushroom Lovers"" (Siberian reindeer favor Fly agaric--""it seems to make them happy""); ""Kinds of Mushrooms"" (one pound of black truffles ""costs as much as a good computer""); and ""Identifying Mushrooms"" (Hydnellum peckii looks like ""a piece of cheese with drops of blood on it""). Arnold's stories from her Russian childhood anchor the book: in one anecdote, Muscovites mistakenly diagnosed an earthquake when ""giant slabs of sidewalk"" outside a museum were ""lifted"" by teams of tiny mushrooms. Fungal fervor at its most contagious. Ages 6-10. (Mar.)